Railway traffic controlling apparatus



2 Sheets-Sheet l 0am W @L wm Sv w@ M W Io||, f T www!! www A um A @W H Filed Oct. 17, 1941 Nov. 16, 1943. G. R. PFLASTERER RAILWAY TRAFFIC CONTROLTLIING APPARATUS NNN Nov. 16 1943. G. R. PFLASTERER RAILWAY TRAFFIC CONTROLLING APPARATUS Filed Oct. 17, 1941 2 Sheets-Sheet 2 Patented Nov. 16, 1943 Y 2,334,506v RAILWAY TRAFFIC CoN'TRoLLING APPARATUS George R. Piiasterer, Greenville, Pa., assignor to The Union Switch and vSignal Company, Swissvale, Pa., a corporation of Pennsylvania Application October 17, l1941, Serial No. 415,397 v 11 claims. Col. 246-160)V My invention relates to railway trafiic controlling apparatus, and more particularly to approach locking apparatus for use in interlocking systems for railroads, for locking a track switch against operation under certain conditionswhen a signal governing movement of traic over the switchfis manually put to stop. The purpose of such lock-V ing is to prevent movement of the switch whenra trainis approaching at such speed that it cannot be readily stopped without overrunriing the switch.

In such a situation, when the stretch of track leading to theswitch is occupied, it is customary to prevent movement of the switch'until after the expiration of a time interval long enough to per-r mit the train approaching the switch either to stop or to advance into the. detector section'and render the detector locking eiective.

The systems of this type heretofore known have employed a fixed time delay period during which operation of the switch is prevented, and the systems operate so that the full time delay period is required to elapse regardlessof the location of the train in the approach zone, `and regardless of the speed at which `the train is ap- Y proaching the switch. This arrangement provides a safe system,- but it may unnecessarily def` lay'train movements.

It is an object of this inventionto provide proved apparatus of the type described andincorporating means to vary the time delayinterval in accordance with thelocation of the train in the approach zone, or with the speed of the .train approaching ythe switch, or both, so that a; short time delay period is enforced at times, and along time delay period is enforced at otheritimes.,

` Other objects of the'invention and features of novelty will be apparent from the following descrip'tion taken in connection with the accompanying drawings. l

I shall describe two forms of apparatus `enrbcdying my invention, and shall then pointrout the novel features thereof in claims,

)inthe drawings Fig. 1 is a diagram showing a `system arranged vso that a short time delay period is imposed whenV the portion of the approach zone in the rear of the distant signal is occupied, and a long timev delay period is imposed when the portion of the approach Zone in advance of Vthis signal is occu-V pied, and t t Fig. 2 is a diagram showing a system'arrangedso that a short time delay period is enforcedV when a slow train approaches the switchandV al "long timeV interval is enforced is approaching the switch.

Similar reference Characters refer to similarv parts in each of the two views.

Referring to Fig; 14 @of the drawings, there is shown therein a stretch of railroad track having a main trackA, and a siding or branch track B the switch W and the which is connected with the main track A bya track switch W'. The switch Wis moved between the normal and reverse positions by a power operated switch machine SM which may beof any Well known construction,land which is controlled by Ya polarized switch customary manner.

The main track A has-*track vrails l and 2 which are dividedby insulated jjoints 3 into the' usual tracksections which are here designated IT, 2T, and 3T. i, The track sections' IT and 2T' together constitute an 'approach stretch `or approach zone, whilefa detector section .iTincludesi adjacent portions of thetracks A and B. f Y

Each of the track sections is provided with track circuit apparatus which may be of any well known type. `As shown each section has aftrack battery connected across the rails of the section at one end ofthe sectionjand a track relay TR connected across the rails of the vsection at the other end of the section.

The maintrack `A is provided with wayside sig` nals which govern movement of trains through the track stretch inthe normal direction of traffic, that is, Yfrom left to right.` The wayside signals may be of anysuitable type; and are here shown The homesig` nal at the switch W has an upper portion desigas being of the color light type.

nated SA which governs movement olftrains through the main track Aacross thevswitch W, and a lower portiondesignat'ed SB which governs movementof "trains from the main'track A across the switch W to the track B.

The signal SA hasa green or clear Vlamp G,a yellow or caution lamp Y, and a red orstop-lamp R, while the signal SB has a yellow or` proceed lamp Y, and a red or stop lamp R. Y v

A distant signalSD is located some distance from the switch W, this Vdistance being such that trains traversing thev track stretch and receiving a restrictive indicationV at signal SD will be able to stop before reaching the switch. The signal SD has a green or clear lamp G, a yellow or cau-v tion lamp Y, and a redv or stoplamp R.

` 'Ihefdist'antv signal- SD is controlled in any appropriate manner'by tramo conditions in advance ,of Ythe signal so `that the signal will diswhen a fast train control relay WR the play its read or stop indication when a train is present in section 2T. When section 2T is va,- cant, the signal SD is controlled in accordance with the indication displayed by signal SA so that when the signal SA is displaying its red or 5 stop indication, the signal SD will display its yellow or caution indication, and `when the signall SA is displayirigi its yellow or its green indication, the signal SD will display its green indication. lo`

The means by which the signal SD isy controlled in-accordance'with trai'cconditionslini advance and by the indication displayed `by the'v4 signal SA is old and well knownin the a-rt and:

is not a part of this invention; and.l'iasnotbeerr15v shown inV order to simplify the disclosure;-

Similarly, the signal SA is controlled bytrafiic conditions in advance of thel signal,4 While'rrian'- ually operated means is provided for also' con#y trolling the signals SA and SB. The means by 20 which these signals are controlled is ol'djand'l Wellknown in the art andl'l'as not beer'isloow'nI in order Vto simplify'the disclosure.

The supply of energy of normal or reverse`= polarity to the Winding' of' thes'witch control 25 relay WR vis controlled by appropriate means; suchv as a lever L.r This leverrnay loe'lo'cated'r at any convenient'po'int, a's for example inA a signal control tower, and may iorrnI apart of an interlockingmachine. Y e 3() The approach'locking'of the switch'is effected` b ynieans'of an approachlockingv relay H which controls the circuit ofI the switch controlfrelay" WR tofperrnit energization of this relay WR`only`y when the relay isenergied, while thefci'rcuit of the relay WR'is also vcontrolled'b'y the' track' relay-STR for the detector section 3T. l

The -relay has associated therewith" aplpreach .relay AR' .a1 signal. indication rel'ay G1 and auxiliary relays M; P -and/Q which cooperate' Il()` as explained below to controlcircuits'rfor' supiV plylng renergy to the relay I-I.-

ando'nly when the signals SA and SB' are'dis'l 4.7

playing their redv orristopf indications', and when', in addition, the signal SD is displaying'either'its" yellow or its red indication.

'rne eireuitef the relay Artis'eentrelldzby contacts of` the track'relays'ITR`and"2TRI s'o' as 50 to be complete o'nlywhen these trackrela'ys are both picked up. Thev relayAR,Y therefore', is picke'dup .only when the approachzon'e is'vvac'ant; and is released wheneither sectionl of tlniszc'irieA islocupied.

The equipment is'shown in the condition wlih' it4 assumes when there are no trains in. tlfief track ,stretch 'in Vthe vicinity of vthe :switcfli YW, thel switclrW is in its normal. position',Y the' signals SA and SB` both ldisplayutheirv red"l 0'r` 60' stopy indications, andthe signal SD displays`-its" yellowfor caution indication. K

A Asthe approach apne eisassinried` to be vacant, the track relays,v I'lRV/and'ZT'Rna're'v 'pickedup and energy vis supplied to'the relay'Alftv over the G5 circuitA which is traced from terminal" of a sourcethreugh front contact'- Id. of relay" ITE,-v vvire (II, front contact I2 of .relay ZIR,r` and Windingtofl relay AR' to terminal C of` the source sothat contactId-*of rela'yAR isV picked'up. A 7()Y As the signals'SAand SB are both' assumed to bedisplaying; sto'p indications,` and as the4 signal SD is assumedto: be displaying its yellowr org-caution indicati'n,A energy is, supplied to` relay G and its contact I5 is picked up. 'f5'y As contact I4 of relay AR and Contact I5 of relay G are picked up, the pick-up circuit of relay I-I is complete and is traced from terminal y B of a source of current through front contact I5 of relay H, front contact I4 of relay AR, Wire I6, and Winding of relay H to terminal C of the source Y e Accordingly, .thf'contactsxof relely'l are picked up and its contact i8 establishes a stick circuit toqmaintain the relay winding energized after between' its'tw'o positions.

As contact 25 of track relay ZTR is picked up, the circuit of relay P is interrupted, and as contact; lilf of relayi'I-fi is pickedup, thefcircuitof the relay' Q isi'ilterriipted-- Ascontact'-4 26 'of relay?v referee-sedi the ple'led-upJ-eircuitl off?re'lryfr If the operator wishes'y to clear' the signallfSA Y he may do so by'neans'fnotlshown, and'wheriw' the signal control apparatus' is-'vco'nditioned' to green or clear indication* as-thieitracl stietclj' linterrupts' thepiklup" and stick circuits-for relay'V H sov 'that'x the contacts` of 'relay'` Hf' release' and its" contacts I I9 and2 2 il; interru'pt th`el circuit'- ef 'relaywa te thereby prevent* movement er1t I-WhiletTietrain is insection IT, and .beforen it enterssection 2Tthe:oioerator 'decides :to change' the v position ofx the switc'lN/V, -he v'rnay do so after expiration of arsliort'timefinterval providing: he*` secures control of* the' switchbefore the` train' passes signal SD vand enters' section 2T. v i Y Y Inorderto secure' controlt of\ thel switch' the operator must rst --cau'sel signal-fSAfto1 again :dis-- play-its stop indication,m while'when this lsignal` shows stop, the signal SD will displayffits yellow or caution indication. When signal-SAshows stop and-signal SD sho-Ws caution,r energy `is sup-Y: plied to relay G- andits contaoteIS'picksj up and-f establishes a circuit including back-contact` I81 o f relay H,.wire.30, and` back contactSh-of'relay P for supplying'l energy. to the slofw vpick-up relay, Q. lAfter a` predeterminedtiine interval the contacts of the relay Qpick up? If at the time thelcontacts of'relay` Qmpick up the train- JinV section I'I` lias` noth advanced int'o section 2T and track relay TFR,"is'p'icked'up;Y a pick-up circuit will be established lorY relayHl 'Ifh'is circuit is' traced'v fro'rn te'rinirial 'B' 'through traclirelay z'rRjwire' salfe'n't contact 35er relay this time.

to one terminal of thewinding'of Q, ,and ,wire' I6 relay f Y Accordingly, energy will be supplied to relay H and its contacts will pick up so that its contact I8 establishes a circuit to maintain ,the relay energized as long. as the contactrl of relay G re-v mains picked up. Y y On picking upof the contacts of relay Hits contact I8 interrupts .the circuit for `supplying energy to the `relay Q so'that relay Q releases,

and its contact-2i;v interrupts the circuit traced above for supplyingenergy to the relay H. However, the relayH is maintainedenergized by current supplied over its own front Contactr I 8, and

contacts I9. and 2B of relay H are picked up and f the circuit ofthe switch control relay -WR iscoml plete' so that the switch W may bemoved.

Movement of the switch at this timeis proper as the train approaching the switch will have received a restrictive indication when it passes signal SD and willlbe approaching signal SAV pre.-

pared to stop.

After completing movement of the switch the operator may condition theappropriate one :of'

ther movement of the switch.

If the train advances into section 2T before the operator decides to move the switch, or before he obtains control of the switch, vvalong'er time interval must elapse before the operator cansecure Vcontrol of the switch. 1

When a train is present in either section IT or 2T, relay ARis released, Vwhile whenY the train 'On release of relay Q the pick-up circuit of relay M is complete and is traced frornterminal B through backcontact 38 ofrelay Q, front contact 26 of relay P, and winding of relay M to terminal C. Accordingly, `the contacts offrelay M` pick up and its contact 39 establishes a stick Vcircuit for the relay. This circuit is traced from terminal Bthrough front contact `I5 of relay G, back contact I4.of relay AR, backV contact,v 21 of relay H, front contact 39 of vrelay M, and winding of relay Muto terminal C. The contacts of relayM,therefore, will remain picked up after release of the contacts of relay P.

Y On release of the contacts Vof relay P the circuit traced above for energizing the relay Q is reestablished, and after a time interval the con- `tacts of this relay pick up with the result that apick-up circuit for the relay H is established. This circuit is tracedlfrom terminal B through frontfcontact I5 of relay G, front Contact 4l] of relay M, wire 34, front contact of relay Q, wire advances into.- section 2T, track `relay 2TR releases. l Asthe signal SA or SB is assumed to be displaying a proceed'indication, VrelayG is` deenergizedand its contact I5 interrupts the cirl cuit of thelrelay H so that the contacts of relayi H are released. v

I f the operator now causes the signals SA and SB to both display stop indications, relay G will be energized and its contact I5 will be= picked up. At this time contact I4 of relay AR is released and interrupts the pick-up circuit of relay H so that relay H remains released- VOn pickingr up of relay G energy is supplied to relay Q over the circuit which is traced from terminal B throughV front contact I5 of relay G, wire I6, back contact I8 of relay H, wire 30, back contact 3l of relay Rand winding of relay Q to terminal C. After a time interval determined by the pick-up time of the relayQvthe contacts of this relay become picked up, and as section 2T is occupied and track relay 2TR is released, its contact 33 interrupts the circuit traced above for supplying energy to the relay H so that the operator does not secure control of the switch at On picking up of the contacts of relay Q a `circuit is established to energize the relay P. This circuit is traced from terminal B through back contact 25 ofl relay ZTR, windingof relay P, and front contactrl of relayQ to terminal C. On picking up of the contacts of the relay P its Contact 3l interrupts the circuit of the relay i6, and winding-,of relay H to terminal C. Accordingly, the contacts of relay H pick up and contact Zlinterrupts the stick circuit for relay Y Ylvl-while contact'I8 of relay H interrupts the circuit of relay Q and establishes a stick circuit Vto energize the relay H as long as relay G remainsV energized. Y

VCn picking Vup of the contacts of the relay H the circuit oi the switch control relay WR is complete providing the train has not advanced beyond the signals SA and SB and entered Vsection 3T so that the track relay 3TH. is released and renders the detector locking eective. Accordingly, on picking up of the relay H the operator obtains controlof the switch and may move it to either position.

It will be seen that after a. train Yenters section 2T,the operator can secure control of the switch 4only after the expiration of a Vtime interval determinedby two operations of the relay Q. This time interval. is long enough to permit the train in section 2T either to stop or to advance into ,section 3T and thereby render the detector lockexpiration of a short time interval when a train is in the section in the rear of the distant signal, while the system operatesfso that when a train is present in the section between the home and distantsgnals, the operator can obtain control of the switch only after the expiration of a longer time interval.

It will be seen that the system provided by this invention operates to permit the switch to be moved only when it is safe to do so, while the system valso operates so that movement of the switch is not delayed anyV longer than is necessary.

- Whena train isin the section in the rear of the distant signal, av short time interval is imposed before the svritch can be moved. Thisis suflicient as the train will receive a restrictive indication from the distant signal and will be prepared to stop before it reaches the switch.

'ff the train is in the section in advance of the distant signal when the home signal is placed at stop, a long time interval must elapse before the switch can be moved. This insures that the train `can either stop before reaching the switch or that it will overrun the home signal and render locking is released.V

Furthermore; the system isfarrangedofthatlif theftrainewhich wasfin the :sectionin/.tha rear-ofi' thev distant signalfat the timertheehomefsignal was placed at s. stop .should` advance beyond` the. distant .signal before thei-"exlziiration ofv fthe:v short 5 i timefintervalj the `operatorscannot obtain controlli ofA the :switchiuntil' the... expiration L ot the z. long: tineintervall This imethodi'ot'operation insuresi thatitheswitchpcan hefmoved after thefexpiraa tion'lof the?v short :time vinterval?.only if ther-.traite l0 issinthe rear of the distanttsigiial forca 'suli'-.Av stantial period afterfthis signal"haszbeencausedf to display its caution..indi'cation'so'thatl'theengineenof thetrain has lample opportunityto view ansa;

interrupts.'therfpick-upandnstck circuitsfrrelayf I-I so that the contacts of relay H releaseandl interrupt ithelcircuit :of fthe 'switch .controlrelay Wltospreiventmovementof the switclrsWw4 Ifv attrainmoving.;l from.- leftto rightV enters section IT the; track/:relay I TR1/*Will .release ande its Contact I0 will interrupt the'lcircuitf-of-f'theA approachzrelayi ARsothat contactz I4otrelay AR interrnpts theepiclc-.up ircuit of the: relay;z iHtocpreventnen'ergization@ of thehrelay Hl'inithe: eventzof f'pckingsup ofLthef-contactf I Soff'relayGgf- Iflafterl thez traini. enters lth'e Asection IT,V thfefi operator pllacestheisignal- ASA5 at stop; theisign'alfi SD IWil 'displayiI its rcautionzindicationf.andfenergy 1f the signal.. 15-rwiil1sbe iippliedrto thei--relayJG'so'that contacty The system provided lby this invention mayialsof. befemployed tovaryftlie time delay interval'infaccordance with theispeed` atwhich aitrainfisl' approaching the switchsothat a shorttime in'- terval is imposed .'whenafsslow train is approach# 20 ing the switchwhileaxlongftime .interVaLis im'- posed when a fasti train: is 'approaching the switch, and Fig.V 2. is a.. diagramshowingethis modication.of.the.invention. i

The modification shown .in Fi'gi' 2 -is "similarto -25 that? shown in" FigrL-'butdiffers therefrom in thatthe track stretchiintermediate the signals SA and SD is divided into two sectionsdesig' natcdY A2T and1B2T.,` while .an additional auxiliary relay. V is...employed.lto'assistin thecontroll 30 ofthe relayH.

The equpmentlofJ-Fig. 2;:isshownin the condi tion which iti assumes when :there are no-trains` in the track stretch in the vicinitycf the switch W, the switchvVf is in'.itslnormalposition, the 35 signals SAA andlbcth display theirredior stop" indications, and the signal SD displaysfits-yel'low or. caution indication.A I

As the approach zone isassumed tcl-be vacant; the trackrelays ITR, A2'ITR.y andiBZTR-are picked r 40 up,y and energy is supplied' tol the relayv ARI so! that its contacts are l pickedupr Asthe homeI signals SA and. SB: are both assumed to be dis' playingstop indications, andasthe dista-ntsig-v nal SD is assumed to be displaying it'scaution 4 indication, energy: is :supplied: to, the relay G1 and its contact. i-is picked up. As-co-ntact Ii'ifofrelay G` andcontactl i^-of1relay ARV areipickedup, the .pick-up.. circuit o-freiayT- is complete,- andfthe contacts of; this relayz are pickediup-.sol 50 that'` Contact: I8: establishes a stick: circuit to" maintainY the contacts ofI relay. H'. picked'lup-aslongY as Contact. ISiOf-relay G is` pickeclaup;Y

As contacts i9' and- 2050i. relayv Hfare# pickedVA I5 fofiltnisarelayspicks-iup and@estalclis'hesA a= cir;A

cuit to energizeerelaylQ'J Thisrzci-rcuitlis tracedf'g" fromrterminal Bi throughV front? contactf I5of relays-Gi;'back contact-,fnl 8f offrelayv H; backicont'actf 3 I- :of rela-575139,'andiwinding.t of frelayQl-'toterminati C-.. After a; time: interval"thel contactsof1-th'ei relay Q pick up, and if they pick uplbeforethe train i' advances: into" 'section i A211? .al-picikup Scircuit s for therrela-yfH;will".he estalclishedf` andj the:contacts :of i relay: Hlwill pickiup c andiestabf-# li'sh fa. sti'ck:lcirouitfforfthe= relay#` and I alsoue'stalb` lish Ythe fcircuiti -of.the-'switclfit control relay WR f toapernfiittheT switch.toibemoved.T

The .pickleup circuitz: for;- therelay-f H'y which istY established- 'onf picking flupof.- thef contactsmf thefrelay Q is traced from/terminal .B throughfronti.

If, therefore, the train'ilrerrr'ainsK in fse'cticxif-ITJ until. afterlthe Vcontacts of'relay iQ become-picked, uptheperato'rf WillS-secure"-control ofthe fsw-itchL after lione operatioriof the contacts-1 ot'the-relayff w-illr. have# been'linrltlnatisection-1frfa#substantial` timet intervalandthei engineer ofi theftrain. w-illf have-had?v ampleopport'unitya to see'thedistanti? signa-l SD. 7 Y Ifithe traini-- advances# -int section before ther-contacts ofrelay Qabe'come picked-Anp, con'- tact 43I ofil track f relay;D AEZYIRWill-'be released' soA that onfpickingv up of thecontacts of-*re'lay Q1: the.;y alcove'I traced:.pickaupicircuitffor the relay* "=H will not loe-established; Insteadfapickuncircuit .fcrfthe relayiVv will'be .establisheel;I This circuit isfftraced from'fterrninal VBthroughffronti" contacta: I 5i of: relay..fG;= backs contact I 4L ofrelaj73 l.loackff contact; ZT# ofi rel ay.' Hg 2 front contact up, and as the contacts 22 and. 23 off'relafyL3T-IR 5T5 445ofirelayBZfIlR'back:contactli'offrelay are also picked: up,. the: circuit Yof. the. switch control relay WRziscomplete andi the operator.'i may change thepolarityrof the;energ-yfsuppliedto this relay and:therebycause'itheswitclrtofbe.2 movefh4 Y Y 60 At this time contact I 3 of relay H interrupt'sf the circuit` of .the relay Q,.. contactvI-wot relay Q. interruptsrthe circutof therelay Pg'contact 26- of relay E interrupts the-circuit .of relay-:My andv contact 43. of.. relay: AQTR..interrupts-tha 65 pick-up circuit of relayzV. Accordingly, the-re'- lays M, P, Q and V arereheased;

If; the operator wishestol clear the signal SA, he g may dorso. by; means not-showmandltlnisI l Thefpick-'up-,timefof :the relayav andthe-lengthf the predeterminediratea- This-predeterminedratef 1 andflfthe length" offthe lsection BZT are=suc`li that"- ai. traini traveling at"tl1is-{or-l a`r slower-rate Twill be able 1tov'sto'p Without dii'ficultyi before Teaching" thefswitchg. 1

Aft'er'iai predeterminedtime intervalfthef consignal will thereupon; display. its .greenoivclear 7o: tactssclrelay/Vfipicl up;lass'uming that^the-trainf indication as the: track.. stretch.. ini advance is: vacant. On this;- change; in=` the` aspect'. ofi-signal, SA signal SD willdisplayjts lgreenfonclear'in-l dication, while onithis. changefi zthelaspects of the signals relay G releases and1'its:contact.-I575with contaotfkloff'relayQ te'establislfi'farpickupi`Z circuit for relay H. V'rms piek-up circuit. for relay H is traced from terminal B through front contact I of relay G, front Contact llof relay relay V and the operator will have control of the l switch. This is proper as the train must -have been moving slowly not to have passedthrough section AZT-before the contacts of relay V become picked `.up and the' train will beableto stop before it reaches the switch. Y

When the contacts of relay H pick up,l contact I8 establishes a stick circuit to maintain therelay energized, while Acontact I8 interrupts the 1 circuit `for supplying energy to the relay Q soV and contact 4I of relay B2TR will interrupt the t pick-up circuit of relayV and thus prevent pick-` ing up of the contacts of this relay.V In addition, on release of the relay BZTR its contact establishes the circuit of the relay P. This circuit is traced from `terminal B through back con-V Y tact 25 of relay BZTR, winding of relay P, and Yfront contact 310i relay Q'to terminal C. 2

Accordingly, the contacts of relay P pick up and its contact 3| interrupts the circuit ofthe relay Q,`while contact 26 of relay P establishes a circuit to supply energyto'relay M after releaseV of the contacts of relay Q. As a result of interruption of the circuit of relay Q by contact 3| of relay P, the contacts of relay Q release andl contact 31 of relay Q interrupts the circuit traced above for energizing the lrelay P so that the contacts of relay P release. However, because of the slow releasing characteristic of the relay P the contacts of this relay remain picked up for'a short time interval subsequentV to release of the contacts of relay Q so that a pick-up circuit including back contact 38 of relay Q and front contact 26 of relay P is established to supply energy to the relayvM. The contacts of relay M, therefore, pick up and its contact 39 establishes a stick circuit to maintain the relay contacts picked up. This stick circuit is traced from terminal B through front contact I5 of relay G, back contact I4 of relay AR, back contact 21 of relay H, front contact 393V of relay M, and winding of relay M to terminal C.

O n release of the contacts of relay lP following release of the contacts of relay Q contact 2e of relay P interrupts the pick-up circuit of relay M, but this relay is maintained energized by current supplied over its stick'circuit. On release of contact 3l of relay P the circuit of relay Q is reestablished and this relay starts a new or second cycle of operation.

After a time interval the contacts of relay Q become picked up and a pick-up circuit for the relay H is established which is traced from terminal B through front contact I5 of relay G, front contact 4!! of relay M, front contact 41 of relay Q, wire I6, and winding of relay H to terminal C. Accordingly, the contacts of relay H pick up and.` its. contact vI8 establishes a circuitito maintainthe relay winding energized, while its contact I8 interrupts the circuit of relay Q and its contact 21 interrupts the circuit of lrelay M so that the contacts of these relays release. As'the contacts ofthe relay H are picked up, the circuit Vof the switch control relay WR'is complete and the-operator may move the switch as desired. i

From the foregoing it` will be seen that the system shown in Fig. 2, likeV that shown in Fig. 1

Voperates so that ifthe operator attempts to secure control of the switch while a train is in section IT, and the relay Q vcompletes one cycle of operation before theltrain enterssection A2T, the operator willY obtain control of the switch after the expiration of the time4 interval required for the contacts of the relay Q to pick up.` Y

However, if the train advances into section :AZTv before thecontac'ts of relay Q become picked up,

the operator will not secure control of the switch upon picking up of the contacts of relay Q. 3 Instead on entrance of the train into section AZT a circuit for the relay V is established. If thespeed of the train is such that the contacts of relay V become picked up before the train traverses section A2T and enters section BET, the contacts of relay V will pick up and establish a pick-up circuit for relay H to thereby give the operator control of the switch. However, if the train speed is such that the train advances into section B2T before the contacts of relay V pick up, thev circuit for energizing relay V is interrupted, whilethe system operates like that shown inV Fig. l so that the operator secures control -of the switch only after two cycles of operation of the relay Q.

This methodl of operation provides a safe system as it permits. the operatorto gain control of the switch after a short time intervalproviding this interval is completed before the train passes the distant signal and enters section AZT. If this short Vtime interval does expire before the train enters section AZT, the system operates to` give the operator control-of the switch after Vexpiration ofV a'further short time interval if the trainis `traveling at a slow speed. This is desirable as it enables the operator to quickly secure'control of the switch at times when a train 'in the approach zone is moving slowly and the attempt to' secure `control of the switch is not made until the train is relatively near the distant signal so that it advances beyond this signal and enters, section AZT before sucient time has elapsed for the contacts ofvrelay Q to become picked up. It is safe for the operator to secure control ofthe switch atsuch times as the train is moving slowly and will be able to stop before reaching the home signal, while ability of the operator to quickly gain control of the switch at such times enables him to route trains Vwithout delay and .thus facilitates movement ef traic across the switch.

The system provided by this invention is safe as the system operates when ,a fast train passes through the approach zone to prevent acquisition of control of the switch by the operator until the expiration of the time interval determined by two cycles of operation of the relay Q. ThisV time interval is long enough to enable the train either to stop or to overrun the home signal and enter the detector section and thus render the detector locking eiective. t

Although I have herein shown and described only two forms of apparatus embodying my invention, itis understood that various changes and. modil'ca'tons .,mayvbel. madez-ftlrereim within Ytl'relsco'peof the appended; claims Without depart'- and'jefljective when" deenergizedzto prevent movement"of"`tl'i'e. switch; means effective when said st section isoccupiedand Saidiocking Vrelay is deenergizedto establish a circuittov supply energyto the lockingrelay after the expiration oflaipredeterminedtime interval,y means responsive tot occupancyoi-"said, second section. for interruptingaidjcircuit. for, supplying` energy to saidlocking relay, asignal governing movement of traflic.,across switch',.,and .means. for deenergizing `said. locking` relay when said signal indicates proceed: andito'permit energy tnbesupplied to saidlockingsgrelayg'onlywhen said signal indicatesstopn Y 2.f.vIn. combination, .aastretch .of :railway l track containing; ansvvitch movable between a.v normal andareverseposition and.,includingl anapproach zone-,of-'tracklleading-t0 sai-d switch, saidapproach zonef-beingfidivided into Aa-plurality 1 of tracksecf tions; including; a rstsection remote from the switchand a second section adjacent .the switch, an` lapproach' locking relaycontroll-ing-the switch and-,effective whenfdeenergized to prevent movementyof thefswitcha a timing relay having a normally open.- contactwlricli on the supply ofv energy izo-theY relay becomes ,-closed onv the-expiration iof arfpredeterfmined,time-interval,- afpickvup .circuit fori said locking. jrelay includingT in series therewitlra contactvofisaid timing relay, means eiec- Ativer when said. frst -section :is l `occupiedsand the locking `relay is-deenergizedcto. establish .a circuit tocsupply; energy Ato vsaid timing re1ay,n1eans responsive lto-,occupancy =ofy saidy secondsection ,for interrupting/inthe. pick-.up vvcircuit for .said 'locking relay,; asignal governing movement', of ftraftc across` saidsvvitch,A Iaridrneans for deenergizing said lockingrelaywhen said signal indicates proceed and to.permitenergyto4 be supplied to said locking relayonlywhen saidsignal indicates stop; 3. Inconibination,l a stretch' of railway track containingpa, switch movable between .a Ynormal andarreverseposition, an apploach'zone of track leading `:to said ,'sWitch, said 'approach zone. being dividediinto .aplurality of, 'trackv sections 'includingraiist vsection remote vfronr'the switch and. a second section. adjacent the switch; 'each- -of Asaid sections being provided with -a trackV relay which is releasedwhen the section isoccupied-,an ap'- proach Vlocking relay controlling the. switch'- and effective when deenergized'* toY` prevent movement :of 'the switch," a'slow pick-upr'relay Y having ancrmally open contact 'which' onthesupply of energy` to the relaybecomesclosed on the expiration of a predetermined timedntervaLa slow releasing relay;anauxiliaryrelay, azcircuit including' backicontacts of 'theflocking relay and said slow releasing 'relay for supplying .energy toy said slow pick-up relay, a circuit including afront contact-ofsaidl slow pick-uprelay and la back Contact"of-'fsaid-` second'v'sect-ion track relaygfor supplying yenergy'tol saidy slow.v releasing relaygfV a accasion circuit including a; front contactof the slow-re leasingrelay and abackl contact of the slow pick.- upgrelaygforsupplying-energy to the auxiliary'relay; aA pick-up circuit for the lockingr'relay including front contacts of the second section track relay andjof saidv slow pick-up relay, a third pick-Y upzcircuit -for said'elockingL relay'. including riront contacts of rsaidf :auxiliary relay and.y offlsaidislow pick-unrelay; a fourth pick-up circuit over which energyfmaygbe'supplied tosaid lockingrelay when the track'relaysfor saidl rst -andf second sections areffpicked upgv a signal governing movementcf traiic 'va-cross said-switch;` and-'means for deenergizing saidslookingffrelay-when said signal indicates proceed and tofrpermitthe pick-up" circuits for said locking -relayto be established. onlyfwhen saidasignal indicatesl stop 4r In combination; astretch lof railwayftrack containing :a yswitch movable between-ak `normalv and-ia reversefposition and including lan approach zone' oit track 'leading' to- -said .sWitch,. said -.ap; preach zone-being divided into a first sectiony remotexfromthe Fswitch,V af secondsectionf adjacent the switch and arrfintermediate-sectione located between said rst and second sectionsfialock relay-controlling'fthe switchy and' eiective'when deenergized tofprevent movement of the'switch, means effective when said, first section ris occupied" for; establishing a' rstpick-*up circuit` to supplyenergy .to 'said lock--relay'lafter-the ,expiratiorr'jof a predetermined time. interval, means eiect-ivei on occupancy' o-- said intermediatey sectionfgto ,preventestablishment of, -said rst pickup circuit, means `responsive-to :occupancyof :the intermediate sectionfor establishing'a second pick-upcircuit Ito supply energynto said lock-,relay after :the expiration,y of; :aY predeterminedtime intrevaL. meanseiectivefon occupancy of said secondi section zto 'prevent establishment l ofl l said second 'pick-up` circuit,. means responsive-to occue par-icy of :said second section {for-l establishingI a third pick:up circuit tosupply4 energy to said lock relay after they i expiration ot a'predetermined time. interval,y a signal.- governingv ,movement of traffic across saidrsW-itch, andmeans for-deenervgiaing lsaidl lockrelayv when saidsignal indicates proceed -and topermit the ,pick-up circuits. for said `lock relay' torbeestablislfled only when said signal indicatesl stop-.1

5.= In combination, ,astretch foffrai-lway track containingra 1 switchA .movable between. a nor-mal andr a' reverse positionandincludingf an' approach zonet-of track leading i to-said switch', said` appreachI zone :being divided into: a rst section remoteirom the switch,A a= second section, adjacent the vfswitch aind-A an intermediate-sectionnlocated I betWeensaid -iirst andrsecond sections, .each of said section-shaving;'aetrackccircuit including `a trackz relayf which is `released-:When the section is occupied, a lock relay controlling the-switch and effective when deenergized-i to-prevent movement ofthe switch. a-rstandasecondslow pickup relayiga slow releasing relayand an:Y auxiliary relay; a circuit including backcontacts or the lock relay and ofe theslow. releasing-relayV for supplying-energy to: the-rst slowA pick-upvrelay; a rstfpick-up circuit for theflock-relayincluding front contacts of the first slowfpick-.uprelay and of the-track relaysfor theintermediateandsecond sections,- a picki-up circuit for .the -second slow4 pick-up,relayincluding a back contact tof the 1 intermediate sectiontrack relayv and'a liront contact of -the=:second :section :track relay,` a1 second :pick-up. circuit for thelock relay including front :contacts of! the erst, .and [second-.slow .pickif up relays, -a circuit includinga back contact of the second section trackvrelay and a'front contact of the rst slow pick-up relay for energizing the slow releasing relay, a pick-up circuit for the and a back contact oi the lock relay, al third pickil up circuit for Vthe lock` relay including front contacts of the Vauxiliary relay and of therst slow pick-up relay, a fourth pick-up circuit over which energy may be supplied to the -lock relay when the track relays forthe-lrst,-intermediate -and second track sections are picked up, a signal gov-3` erning movementY of traffic across said switch, and means for deenergizing said lock relay when said signal indicates proceed and to permit the pick-up circuits for said lock relay to be established only when said signal indicates stop.

6. In combination, a stretch of railway track containing a track switch movable between a normal and a reverse position and including an approach zone of track leading to said switch,

Vsaid approach zone being divided into a first section remote from the switch and a second section adjacent the switch, an approach locking relay effective when deenergized to prevent movement of-the switch and effective when energized to permit the switch to be moved, means effective when said rst section is occupied and said locking relay is deenergized to establish a first pick-up circuit to supply energy to said locking relay after a predetermined time interval, means responsive to occupancy ofthe second section when Said locking relay is deenergized to prevent establishment of said ilrst pick-up circuit and to establish a second pick-up circuit to supply energy to'said locking relay afterV a predetermined time interval. said locking relay being effective when energized to establish a stick circuit to maintain itself energized, a signal governing movement of traflic across said switch, and means for deenergizing said locking relayY when said signal indicates proceed and for permitting the pick-up and stick circuits for said locking relay to be established only when vsaid signal indicates stop. l

7. In combination, a stretch of railway track containing a track switch movable between a normal and a reverse position and including an approach zone of track leading to said switch,

movement of traiiic across said switchjand means for deenergizing said locking `relay when said signal indicates nroceedand for permitting the pickup and stick circuits" for said lockingvrelay to be established only when saidsignal indicates stop.

8;"In combination, a stretchqof railway track containing a track switch movable between a normal l and a reverse position and including an approach zone of track leading to said switch,

said'approach zone beingv divided intoa first section `remotefirom the switch and a second sectionadjacent the switch, an approach locking relay effective when deenergizedA to preventmovement of" the switch, meanseffective when: said iirst section is occupied, the" locking relay isdeenergized andthe second section is vacant to supply energy to said locking relay after afpredetermined time interval, means effective on entrance of a train into the second section prior to the expiration of said predetermined time interval to prevent the supply of energy to said locking relay by said rst named means and to supply energy to said locking Vrelay after a further predetermined time interval, said locking relay `being eifective when energized to establish a stick circuit to maintain itself energized, a signal governing movement of traffic across said switch, and means for deenergizing said locking relay when said signal indicates proceed and for permitting energy to be supplied to said locking relay only when said signal indicates Stop.v v

9. In combination, a stretch of railway track t containing a track switch movable between a norsaid approach zone being divided into a first f relay effective when deenergized to prevent move-Y mentV of the switch, an auxiliary relay having a normally open Contact which on the supply of energy to the relay winding becomes closed after a predetermined time interval, means effective when said first or said second section is occupied and the locking relay is deenergized to supply energy to said auxiliary relay, means effective on closing of the contact of said auxiliaryrelay when said second section is vacant to establish a pickup circuit to supply energy to said locking relay` means eiective on initial closing of the contact of said auxiliary relay when the'second section is occupied to interrupt the supply of energy to said auxiliary relay and Aeffective on the second closing of said auxiliary relaycontact tovestab'- lisb a pick-up circuit to supply energy to said locking relay, said locking relay being effective when energized to establish a stick circuit to maintain itself energized, a signal governing mal and a reverse position and including an approach zone of track divided into a plurality of sections including a first section at the end 0f the approach zone remote from the switch, an approach locking relay effective when deenergized to prevent movement of the switch, means Yeliective when said first section is occupied, the

lockingrelay is deenergized and the remainder of the approach zone is vacant to supply energy to said locking relay after a predetermined time interval,`means effective on entrance of a train into theportion of the approach zone intermediate said first section and the switch when the locking relay is deenergized to prevent the supply of energy to said locking relay by the first named means and to supply energy to said locking relay after a furthertime interval ofone t permitting energy to be supplied to said locking l relay only whe nsaidlsignal indicates stop.

l0. In combination, a stretch of railway track containing a track switch and including an approach zone of track divided into a plurality of sections including a iirst section at the end of the approach zone remote from the switch, an approach locking relay effective when deenergized to prevent movement of the switch, means effective when said iirst section is occupied and the remainder of said approach zone isv vacant to establish a pick-up circuit to supply energy to said locking relay after a predetermined time interval, means effective on entrance of a train into the portion of the approach zone intermeudiate'said. Lrstzsectioneandzthef swtohrtd iprevent establishment? .of #said g, pekegup ,zcirquit, a sign@ ..go\fern.ir3g'L movement-of, traicacrosse-sadf swith, amd :means ,l lfor deenergiziiig; said flocking `:,relay fwwhen said .signalgindicaftesg/proee ed; and; -forftperimittirigf'energyt tol ber suppliedvtofsaidioclsirig re- :my .only-whern -said s ignali-indica-tesf stop.

1 1. lIn -combinationmaf stretch, of railwvayfstraek :containing ai track switclfiandl includiiiigianfappreach zoney .oftrack divided,-ntofap1ura1ty -o-f Y fsectonsffincludfng; ayrstV section Yat ;the end: of Athe gpproachvyzonefremote-:from the switchen h:thei-renrlaindeAr'A of saidvapproach zonexis Vac-:ant

^ toffestablisha piek-up 1 circuit tor supply energy AtousaidQl-loeking; relayv after;a=a;-predtermined time 'l interi/m1,: meansfeiectivewom entrancefof z a .train into,'.the; portion ,of the approach.` zone. 4interme- 5 Ldiate said: first sectioma-nd theasWi-tch 'tdprevent establishment fof -said :pick-up circuit and Ato estalJolish-f another. pick-.up ycircuit to supplyen- Vvergy 170; said locking'relay-after aiurtherjpredeter-minedi time intervalfa vsignal*'governing move- GEGRGE-.R.- PFLASTERER.l v 

